Silicone adhesives are a critical component in product efficacy and are used to ensure long term retention in the oral cavity of active ingredients from oral care compositions. Given their importance as ingredients in oral care compositions, it is critical to have accurate quantitative and qualitative information about the silicone adhesive prior to their use in bulk manufacturing of an oral care composition.
A typical means of performing quantitative and qualitative tests on silicone adhesives is to measure the viscosity using a Brookfield viscometer. However, this procedure often provides great variances in the viscosity (even with small difference in instrumental parameters and hardware) of the sample which is not reflective of the entirety of the silicone adhesive batch.
Another means of performing quantitative and qualitative tests on silicone adhesives is to measure the tack (“stickiness”) of the adhesive. Numerous well known tests have been described to measure tack, e.g. probe tack (ASTM D2979), rolling ball (ASTM D3121), loop tack (FTM 9), “quick stick” (BS EN 1945).
However, these tests also suffer from the vagaries of duration of contact, temperature, rate of testing and the skill of the tester.
Both viscosity and tack testing attempt to provide quantitative and qualitative data by measuring a physical property of the test sample. However, one of ordinary skill in the art could achieve the same viscosity or tack data by using an alternative compound/composition than with the silicone adhesive.
Another problem with the previously known test methods is the quantitative and qualitative testing can only extend to the batch of silicone adhesive itself; these tests could not be extended directly to provide quantitative or qualitative data about the end product (e.g. an oral care composition) where the silicone adhesive has been added as an ingredient. (note: the method is more difficult to use for measurement of finished products with a yield stress)
Lastly, manufacturers of silicone adhesives often provide general information about their proprietary products, but not specific information which could enable the end user to reverse engineer their products. As such, another challenge in performing quantitative and qualitative test on a silicone adhesive is to gain sufficient test data to qualify a batch of silicone adhesive without having access to the specific chemical structure of the silicone adhesive.
Therefore, there is still a need in the art for a simple and rapid test which provides improved quantitative and qualitative analysis of silicone adhesives which can also be extended to end products and can be provide sufficient analysis in the absence of specific structural data about the silicone adhesive.